Do not use less or more with executables binary files , such as output files produced by compilers. Doing so will display garbage and may lock up your terminal. These commands print a file on a printer connected to the computer network. Both commands may be used on the UITS systems. To print a file named myfile on a printer named lp1 with lpr , enter:. This command will list the files stored in a directory.
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To see a brief, multi-column list of the files in the current directory, enter:. To also see "dot" files configuration files that begin with a period, such as. If the listing is long and scrolls off your screen before you can read it, combine ls with the less utility, for example:. For more, see In Unix, how do I list the files in a directory? This command displays the manual page for a particular command. If you are unsure how to use a command or want to find out all its options, you might want to try using man to view the manual page. If you are not sure of the exact command name, you can use man with the -k option to help you find the command you need.
To see one line summaries of each reference page that contains the keyword you specify, enter:. Replace keyword in the above example with the keyword which you want to reference. Also see In Unix, what is the man command, and how do I use it to read manual pages?
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To make a subdirectory in a particular directory, you must have permission to write to that directory. This command will move a file. You can use mv not only to change the directory location of a file, but also to rename files. Unlike the cp command, mv will not preserve the original file. As with the cp command, you should always use -i to make sure you do not overwrite an existing file. To rename a file named oldname in the current directory to the new name newname , enter:.
To move a file named hw1 from a subdirectory named newhw to another subdirectory named oldhw both subdirectories of the current directory , enter:. If, in this last operation, you also wanted to give the file a new name, such as firsthw , you would enter:. The ps command displays information about programs i. Entered without arguments, it lists basic information about interactive processes you own.
However, it also has many options for determining what processes to display, as well as the amount of information about each.
For example, to view detailed information about all running processes, in a BSD system, you would use ps with the following arguments:. For more information about ps refer to the ps man page on your system. Also see In Unix, what do the output fields of the ps command mean? For more, see In Unix, how do I determine my current working directory? This command will remove destroy a file. You should enter this command with the -i option, so that you'll be asked to confirm each file deletion. To remove a file named junk , enter:. Using rm will remove a file permanently, so be sure you really want to delete a file before you use rm.
To remove a non-empty subdirectory, rm accepts the -r option. On most systems this will prompt you to confirm the removal of each file. This behavior can be prevented by adding the -f option. To remove an entire subdirectory named oldstuff and all of its contents, enter:. Using this command will cause rm to descend into each subdirectory within the specified subdirectory and remove all files without prompting you.
What is computing with Unix?
Use this command with caution, as it is very easy to accidently delete important files. As a precaution, use the ls command to list the files within the subdirectory you wish to remove.
To browse through a subdirectory named oldstuff , enter:. This command will remove a subdirectory. To remove a subdirectory named oldstuff , enter:. The directory you specify for removal must be empty. To clean it out, switch to the directory and use the ls and rm commands to inspect and delete files. This command displays or changes various settings and options associated with your Unix session. If the output scrolls off your screen, combine set with less:. The syntax used for changing settings is different for the various kinds of Unix shells; see the man entries for set and the references listed at the end of this document for more information.
This command starts the vi text editor.
What is UNIX?
To edit a file named myfile in the current directory, enter:. The vi editor works fairly differently from other text editors. If you have not used it before, you should probably look at a tutorial, such as Use the vi text editor.
The very least you need to know to start using vi is that in order to enter text, you need to switch the program from command mode to insert mode by pressing i. To navigate around the document with the cursor keys, you must switch back to command mode by pressing Esc. To execute any of the following commands, you must switch from command mode to ex mode by pressing: Enter w to save; wq to save and quit; q!
The w and who commands are similar programs that list all users logged into the computer. If you use w , you also get a list of what they are doing.
A survival guide for Unix beginners
If you use who , you also get the IP numbers or computer names of the terminals they are using. This is document afsk in the Knowledge Base. Last modified on Options Help Chat with a consultant. Introduction to Unix commands. The shell acts as an interface between the user and the kernel. When a user logs in, the login program checks the username and password, and then starts another program called the shell. The shell is a command line interpreter CLI. It interprets the commands the user types in and arranges for them to be carried out.
The commands are themselves programs: Staff and students in the school have the tcsh shell by default. Filename Completion - By typing part of the name of a command, filename or directory and pressing the [ Tab ] key, the tcsh shell will complete the rest of the name automatically. If the shell finds more than one name beginning with those letters you have typed, it will beep, prompting you to type a few more letters before pressing the tab key again.
History - The shell keeps a list of the commands you have typed in.
Introduction to Unix commands
If you need to repeat a command, use the cursor keys to scroll up and down the list or type history for a list of previous commands. A file is a collection of data. They are created by users using text editors, running compilers etc. All the files are grouped together in the directory structure.
The file-system is arranged in a hierarchical structure, like an inverted tree.